# 定义一个字典变量
student_grades = {"Alice": 90, "Bob": 85, "Charlie": 78}

# 打印变量的值
print("Student Grades:", student_grades)

# 访问字典中的特定元素
alice_grade = student_grades["Alice"]
print("Alice's grade:", alice_grade)

# 添加新的键值对到字典
student_grades["David"] = 92
print("Updated Student Grades:", student_grades)

# 删除字典中的元素
del student_grades["Charlie"]
print("Student Grades after removing Charlie:", student_grades)

# 检查字典是否包含某个键
if "Eve" in student_grades:
    print("The dictionary contains 'Eve'.")
else:
    print("The dictionary does not contain 'Eve'.")
